Light bulb



FIG. 1 is a perspective view of a light bulb showing my new design;

FIG. 2 is a front elevational view thereof, the rear elevational viewthereof and left side elevational view thereof and the right sideelevational view thereof being identical in appearance;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof.

The ornamental design for a light bulb, as shown and described.